A system of imaging concave and convex portions on a surface of an object, for using the obtained images for inspection, authentication, or the like has been formulated.
For example, Patent Literature 1 describes a light irradiating device including a light diffuser having substantially a plate form or a dorm form provided to be adjacent to and cover the inspection region imaged by the inspection camera, a plurality of light irradiators provided outside the light diffuser to be apart from one another, and transmitting light through the light diffuser to irradiate the inspection region with the light, and a cylindrical member elongating in the direction of the camera from around the hole for imaging and observation provided for the light diffuser, which is configured so that the camera can image the inspection region through the cylindrical member and the hole for observation and so that light from the light irradiator does not directly enter the opening of the cylindrical member at the side of the camera.
On the other hand, attempts to use individual difference in minute convex and concave portions of an object for authentication and verification have started.